Airbag module Z-height control tab

ABSTRACT

A Z-height control tab maintains the distance between an airbag cover and a reaction housing. The reaction housing and airbag cover interlock to define a Z-height. The Z-height is defined as the distance between the two interlocked members. The Z-height control tab extends from the reaction housing and engages a wall edge of a skirt extending from the airbag cover. This Z-height control tab engagement maintains the Z-height by preventing the airbag cover and the reaction housing from compressing together.

BACKGROUND OF THE INVENTION

[0001] 1. The Field of Invention

[0002] The present invention relates to an airbag module housing. Morespecifically, the present invention relates to maintaining a Z-heightbetween two members of an airbag module.

[0003] 2. The Relevant Technology

[0004] In the modern day automobile, the airbag has become as importantan automobile safety feature as the seatbelt. Government standards andconsumer demands have dramatically increased airbag use throughout theautomobile. Airbag deployment occurs when sensors detect an abnormaldeceleration in the automobile, triggering an explosive charge thatimmediately inflates the airbag. The airbag deploys into the automobilecabin, dampening the occupants' acceleration toward any rigid interiorcomponents and preventing serious injury or death. The success ofairbags has caused automobile manufactures to install airbags inmultiple locations throughout the automobile cabin, including thesteering wheel, the passenger side dashboard, and the side doors.However, due to size restrictions of these locations, designers mustoften balance maximum safety with minimum size.

[0005] Airbag modules require accurate and consistent placement of eachmember of the module. Many airbag designs implement similar modulemembers, such as airbags, airbag covers, and reaction housings. Areaction housing and an airbag cover typically mate or interlock to forman airbag storage volume. The airbag storage volume is defined as thevolume between the interlocked reaction housing and airbag cover. Theairbag is placed in a folded state within the airbag storage volume. Theairbag will generally have an inflation opening where the airbagattaches to the reaction housing and the airbag is then positionedwithin the reaction housing to deploy toward the airbag cover. Theairbag cover typically has a front panel that is exposed to theautomobile cabin and a skirt that extends from the back surface of thefront panel. The skirt provides an opening to mate the reaction housingto the airbag cover. The airbag cover is designed to release the airbaginto the automobile cabin upon inflation of the airbag. Airbag coversrelease airbags from the storage volume and into the passengercompartment by using hinged or pivotal doors to release the airbag or bytear-lines in the front panel of the cover that tear apart when theairbag deploys.

[0006] To facilitate deployment of an airbag through the airbag coverand into the automobile cabin, airbag modules typically use thedifferent relative strengths between the reaction housings and theairbag cover. Because the pivotal door or the tear lines in the airbagcover are designed to yield when an airbag deploys, the relativestrength of the airbag cover must be smaller than the strength of thereaction housing. Consequently when an airbag expands, the reactionhousing acts as a reaction surface from which the expanding airbag mayexert an equal and opposite load on the airbag cover. The airbag coveryields to the expanding airbag, allowing the inflated airbag to deployaway from the reaction housing and into the automobile cabin.

[0007] Airbag module designs require consistent placement of each modulemember within the airbag module to maintain a proper airbag storagevolume. As previously discussed, the storage volume is defined as theregion between the interlocked airbag cover and reaction housing. Thecritical measurement in the airbag storage volume is the Z-height. TheZ-height is the distance between the back surface of the airbag coverand the reaction surface of the reaction housing. The Z-height changesas the reaction housing and the airbag cover move relative to eachother. Thus, as the two members are pulled apart, the Z-height increasesand as the two members are compressed together, the Z-height decreases.Significant displacement of the defined Z-height can interfere withproper airbag operation. For example, because airbag covers aretypically an aesthetic member of the automobile cabin, an incorrectZ-height will prevent the cover from sitting flush with the otherinterior components. Also, airbag covers on steering wheels aretypically connected with the horn. If the Z-height is displaced, it maycause the horn to constantly actuate or to not operate at all. Inextreme situations, an improper Z-height displacement can interfere withthe deployment of the airbag. This may cause the airbag to deployincorrectly. Additionally, if a Z-height displacement compromises thecoupling between the reaction housing and the airbag cover, a deployingairbag may project the airbag cover toward the automobile passenger.

[0008] To maintain a functional Z-height, a mode of fastening the airbagcover to the reaction housing must be carefully selected. The fastenermode should be low cost and easy to assemble. More importantly thefastener mode must maintain a proper Z-height when the reaction housingand airbag cover receive compressive and tensile loads. If an inadequatefastener mode is selected, the coupling between airbag cover andreaction housing may fail, causing the airbag to malfunction. A commontype of fastening mode used in airbag modules is an integrally formedfastener. Integrally formed fasteners are manufactured as a part of themodule member to which it is associated. Examples of integrally formedfasteners may include snap fits, slot and latches, and hook and windows.These fastener designs are less expensive than traditional fasteners,such as screws, and require significantly less assembly time.

[0009] An exemplary embodiment of an interference fastener for an airbagmodule is the hook and widow design. Hook and widow fasteners areinexpensive to manufacture and are easy to assemble. They are alsocapable of a wide variety of embodiments. Hook and window fastenerstypically comprise a protruding “J” shaped hook on a first mating memberand a cutout window on a second mating member. The “J” shaped hookslides through the window and engages an edge of the window with thecurved section of the hook. Any tensile load applied to the hook willonly serve to anchor the hook further to the window. This fit is idealfor withstanding the large tensile loads induced by an airbag explodingbetween the reaction housing and the airbag cover.

[0010] Unfortunately, a simple hook is not adequate for withstandingcompressive loads between the reaction housing and the airbag cover.Compressive loads work against the hook and window design by disengagingthe hook from the window's edge. Consequently, designers have addedvarious geometries to the hook to allow for proper maintenance of theZ-height during both tensile and compressive loads. Secondary processes,such as crimping the hooks, have been used to create geometries that canproperly maintain the Z-height. These geometries engage other parts ofthe window or airbag module to maintain the Z-height during compressiveloads. However, these secondary processes can add cost to themanufacturing process of an airbag module.

[0011] Single shot injection molding processes have been used to createhook geometries that can maintain the Z-height during both tensile andcompressive loads while using a single step manufacturing process.Various designs of hook and window fasteners can be manufactured with aninjection molding process because of the ability in molding to controlthe shape of the fastener in three dimensions. The three-dimensionalnature of injection molding allows designers to add steps or shelves toa hook that will prevent compression of the Z-height and reduction ofthe airbag storage volume. Further, the injection molding process mayuse plastics or metals in the airbag module and fastener designs. Theflexibility of injection molding makes it a widely used process inmanufacturing airbag modules. However, despite all the discussedadvantage of injection molding, molding does not necessarily produce thestrongest and least expensive airbag module components.

[0012] Manufacture's seeking to produce the highest strength airbagmodules at the lowest cost have turned to metal stamping processes toform some of the airbag module components. Stamping involves placing agenerally thin sheet of metal over a form and then stamping the sheetinto the form, forcing the sheet into the shape of the form. Stampingcan create various holes and lips in the sheet of metal in a single-stepprocess. Stamped airbag components provide the high strength andductility of metal with the cost effectiveness of a single-stepmanufacturing process. Further, the equipment required for stamping isless expensive than the equipment required for injection molding.

[0013] One drawback with current stamping processes in airbag moduledesign is the limitation of only being able to form objects in twodimensions. The single motion stamping process has been unable, thusfar, to produce a three-dimensional geometry hook or other adequatestructure that can maintain an airbag module Z-height during tensile andcompressive loads without secondary manufacturing processes. An airbagmodule design capable of maintaining a proper Z-height during tensileand compressive loads while also capable of being manufactured by asingle-step, stamped metal process would provide superior strength,cost, and operational advantages over similar injection molded ormulti-stepped airbag module designs.

[0014] Accordingly, a need exists for an airbag module that is capableof substantially maintaining the Z-height of an airbag placement volumein tensile and compressive loads that can also be manufactured by asingle-step metal stamping process.

BRIEF SUMMARY

[0015] The apparatus of the present invention has been developed inresponse to the present state of the art, and in particular, in responseto the problems and needs in the art that have not yet been fully solvedby currently available airbag module designs. Thus, it is an overallobjective of the present invention to provide an airbag module that iscapable of substantially maintaining the Z-height of an airbag placementvolume in tensile and compressive loads that can also be manufactured bya single-step metal stamping process.

[0016] To achieve the foregoing objective, and in accordance with theinvention as embodied and broadly described herein in the preferredembodiment, an airbag module with a Z-height control tab is provided.According to one configuration, the airbag module may comprise areaction housing and an airbag cover. The reaction housing furthercomprises a plurality of mounting projections and the airbag covercomprises a skirt with a plurality of windows corresponding to themounting projections. The reaction housing and the cover interlock viathe mounting projections and the skirt windows to define a Z-height, theinternal distance between the reaction housing and the airbag cover. TheZ-height is substantially maintained during tensile loads by themounting projections and the Z-height is substantially maintained duringcompressive loads by the Z-height control tabs. The mounting projectionsprevent the Z-height from increasing and the Z-height control tabsprevent the Z-height from decreasing.

[0017] In a preferred embodiment the reaction housing is manufactured bya single-step, metal stamping process. The Z-height control tabs arecreated in a shoulder section of the reaction housing as the housing isstamped into shape, thus integrally forming the tabs into the reactionhousing. The Z-height control tabs may also extend from the shoulderportion of the reaction housing at any number of angles, such that theZ-height control tabs engage the top of the skirt in a net tointerference fit. This provides a secure fit between the reactionhousing and the airbag cover. Alternatively, the Z-height control tabsmay be semi-deflectable to facilitate an interference fit with theskirt.

[0018] These and other objects, features, and advantages of the presentinvention will become more fully apparent from the following descriptionand appended claims, or may be learned by the practice of the inventionas set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order that the manner in which the above-recited and otheradvantages and objects of the invention are obtained will be readilyunderstood, a more particular description of the invention brieflydescribed above will be rendered by reference to specific embodimentsthereof which are illustrated in the appended drawings. Understandingthat these drawings depict only typical embodiments of the invention andare not therefore to be considered to be limiting of its scope, theinvention will be described and explained with additional specificityand detail through the use of the accompanying drawings in which:

[0020]FIG. 1 is a perspective view of a reaction housing with Z-heightcontrol tabs and an airbag cover;

[0021]FIG. 2 is a cross-sectional view of the reaction housing coupledto the airbag cover as indicated in FIG. 1;

[0022]FIG. 3 is a cross-sectional view of an angled Z-height control taband window engagement; and

[0023]FIG. 4 is a cross-sectional view of a Z-height control tab andrecessed window engagement.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0024] The presently preferred embodiments of the present invention willbe best understood by reference to the drawings, wherein like parts aredesignated by like numerals throughout. It will be readily understoodthat the components of the present invention, as generally described andillustrated in the figures herein, could be arranged and designed in awide variety of different configurations. Thus, the following moredetailed description of the embodiments of the apparatus, system, andmethod of the present invention, as represented in FIGS. 1 through 4, isnot intended to limit the scope of the invention, as claimed, but ismerely representative of presently preferred embodiments of theinvention.

[0025]FIG. 1 depicts an embodiment of an airbag module 8 with multipleZ-height control tabs 10 extending outwardly from the perimeter of areaction housing 12. The Z-height control tabs 10, as the name suggests,function as part of a system to maintain the Z-height 16 of an airbagstorage volume. The airbag storage volume is the volume between theinterlocked reaction housing 12 and the airbag cover 20. The Z-height 16of the airbag storage volume is defined as the distance from the backsurface 24 of the airbag cover 20 to the reaction surface 28 of thereaction housing 12. This distance is critical to proper operation andorientation of the airbag module 8 within the automobile. To properlyunderstand the function of the Z-height control tabs 10, the componentsof the airbag module 8 and their interaction with each other must beviewed as a whole.

[0026] The airbag cover 20 of FIG. 1 has a front panel 32 and a skirt36. The front panel 32 in the embodiment shown is the member of theairbag module 8 exposed to the interior of the automobile, such as thefront panel 32 of the steering wheel, the top of the dashboard, or theside panel of doors. The skirt 36 extends from the back surface 24 ofthe front panel 32 of the airbag cover 20, creating an area beset by thewalls of the skirt 36. The beset area is sized to mate with the reactionhousing 12. The walls of the skirt 36 have a plurality of windows 40with openings through the sides that are positioned to interlock withthe reaction housing 12.

[0027] The reaction housing 12 comprises a reaction surface 28 with ashoulder portion 44 extending downward from the reaction surface 28. Aplurality of mounting members or hooks 48 extend from the shoulderportion 44 of the housing and form a “J” shape near the end of the hooks48. The hooks 48 are sized to fit through the windows 40 of the skirt 36and engage the edge of the windows 50 with the “J” shaped sections ofthe hooks 48. Other shapes of mounting members or hooks 48 may beimplemented in the present airbag module 8. The hooks 48 may have an “L”or a “V” shaped end rather than a “J” shaped end. Alternatively, thehooks 48 may be a stud with an enlarged head or similar structure.Multiple other embodiments of the hooks 48 may be employed in the airbagmodule 8 so long as the hooks 48 engage the windows 40 and maintain theZ-height 16 during a tensile load. Additionally, the hooks 48 do notneed to extend from the shoulder portion 44 of the reaction housing 12.One ordinarily skilled in the art will recognize various other locationsand methods of coupling the hooks 48 to the reaction housing 12.

[0028] The hooks 48 mate with the windows 40 in the skirt 36 as theshoulder portion 44 of the reaction housing 12 is nested into the areabeset by the airbag cover skirt 36. To facilitate a tight engagementbetween the shoulder portion 44 and the skirt 36, the two members mustbe mateably sized, i.e. substantially the same size. In one embodimentthe airbag cover 20 is made of a semi-flexible material to allow thewindows 40 in the skirt 36 to flex around the hooks 48. The hooks 48then slide through the windows 40. The reaction housing 12 and theairbag cover 20 are then pulled apart so that the “J” shaped ends of thehooks 48 lock onto the edge 50 of the skirt windows 40. Once the hooks48 are fully engaging the window edges 50, the maximum Z-height 16 isset. These hook 48 and window 40 engagements will then substantiallymaintain the maximum Z-height 16 between the reaction housing 12 and theairbag cover 20 during a tensile load, such as airbag deployment.However, when the reaction housing 12 and the airbag cover 20 encountera compressive load, the hooks 48 will disengage from the window edge 50,decreasing the Z-height 16. A large enough load can decrease theZ-height 16 until the hooks 48 abut the backside of the front panel 24.

[0029] To maintain a minimum Z-height 16 during a compressive load,multiple Z-height control tabs 10 are situated around the perimeter ofthe reaction housing 12. The Z-height control tabs 10 extend outwardfrom the side of the reaction housing 12, such that they engage the topof the skirt wall 56 when the hooks 48 engage the edge of the windows50. The tab 10 engagement at the top of the skirt wall 56 determines theminimum height between the back surface 24 of the airbag cover 20 andthe reaction surface 28 of the reaction housing 12. This prevents thereaction housing 12 from sinking below the top of the skirt wall 56during compressive loads on the module 8, such as repeated hornactuation or a passenger striking the airbag cover 20.

[0030] Together the Z-height control tabs 10 and the hook 48 and window40 fasteners function to substantially maintain the Z-height 16 of theairbag storage volume during a wide range of loads exerted on an airbagsystem. The Z-height 16 is only “substantially” maintained because offlexibility and tolerances inherent in an airbag module 8. In anembodiment where the airbag cover 20 is made of a semi-flexiblematerial, a compressive load on the airbag cover 20 may cause a smalldegree of elastic bucking in the skirt 36 when the top of the wall iscompressed against the Z-height control tab 10. The degree of bucklingmay depend upon the amount of load placed on the cover, and differencein stiffness between the tabs 10 and the skirt 36. This buckling maycause a temporary decrease in Z-height 16, but the original Z-height 16will return when the compressive load is removed. Likewise, the hook 48and window 40 engagements or the tab 10 and skirt 36 engagements mayhave tolerance variation that creates an area of travel between the “J”shaped hooks 48 fully engaging the edge of the windows 50 and theZ-height control tabs 10 abutting the top of the skirt 36. Whiletolerance variations allow for some slight change in the Z-height 16,these small allowances in tolerances should not effect the operation ofthe airbag module 8.

[0031] One ordinarily skilled in the art will recognize that the airbagmodule 8 of FIG. 1 is only illustrative of the possible airbag cover 20and reaction housing 12 embodiments within the scope of thisapplication. One such alternative embodiment may vary the shape of thereaction housing 12 and airbag cover 20. The reaction housing 12 and theairbag cover 20 of FIG. 1 are shown as being generally square shaped,however the shaped will vary depending upon the placement of the airbagmodule 8. For example, circular or oval modules may be desirable forsteering wheel applications and thin rectangular shaped airbag modules 8may better serve side door and dashboard airbags.

[0032] One ordinarily skilled in the art will recognize the wide rangeof airbag module 8 designs that can implement the Z-height control tabs10 disclosed herein.

[0033] Additionally, another variation of the embodiment of FIG. 1 mayreverse the reaction housing 12 and the airbag cover 20. The airbagcover 20 may comprise a plurality of hooks 48 and Z-height control tabs10 and the reaction housing 12 may comprise a skirt 36 with a pluralityof windows 40 corresponding to the hooks 48. The two components wouldengage in the same manner as the airbag module 8 of FIG. 1. Further, theairbag cover 20 itself may not be an exposed member of the interior ofthe automobile. The airbag cover 20 may have an aesthetic overlay thatis exposed to the interior of the automobile.

[0034]FIG. 2 depicts a cross-sectional view of the airbag module 8 withthe hooks 48 engaging the window edges 50 across sectional line A-A ofFIG. 1. This figure also clearly shows the measurement of the Z-height16 within the airbag storage volume and the placement of the airbag 58within the storage volume. In the FIG. 2 embodiment, the airbag isconnected to the reaction housing 12 at an opening 60 in the airbagwhich receives an inflating charge 64. Two Z-height control tabs 10 areshown extending perpendicularly from the side of the reaction housing 12and abutting the top of the skirt wall 56. The skirt 36 and the tabs 10preferably intersect in a net or interference fit. A net fit exist whenthe height of the skirt 36 is generally equal to the Z-height 16 of thestorage volume, such that the top of the skirt wall 56 touches theZ-height control tabs 10. Also, to create a net fit the hooks 48 mustfully engage the edge of the window 50 in the “J” shaped ends. This netfit will limit most movement in the reaction housing 12 and the airbagcover 20 relative to each other.

[0035] In an interference fit, the height of the skirt 36 from the edgeof the window 50 to the top of the skirt wall 56 is taller than theheight of the hook 48 from the concaved section of the “J” hook end 48to the reaction surface 28. The difference in heights biases the top ofthe skirt wall 56 against the Z-height control tab 10 when the reactionhousing 12 and the airbag cover 20 are engaged. This biasing loadproduces a slight deflection in the tab 10 or a slight buckling in theskirt 36. The deflection or buckling functions similar to a spring,forcing an engagement between the two members. An interference fitcreates a snug fit between the reaction housing 12 and the airbag cover20, eliminating most variation in the Z-height 16. Incorporating asemi-flexible airbag cover 20 is not only beneficial in eliminatingvariation in the Z-height 16, but it also eases assembly of the airbagmodule 8.

[0036] In the embodiment of FIG. 2, the width between the ends of thehooks 48 and the width between of the ends of Z-height control tabs 10are wider than the width of the skirt 36. To allow for the reactionhousing 12 to be assembled to the airbag cover 20, one of the twomembers must be capable of yielding. One embodiment accomplishes this bymolding the airbag cover 20 out of a semi-flexible plastic. This willallow the skirt 36 to flex outward, providing a space for the hooks 48and Z-height control tabs 10 to fit through the inner width of the skirt36 until the hook 48 slides through the window 40. The reaction housing12 and the airbag cover 20 are then pulled in a tensile direction tolock the hooks 48 into the window edges 50. This tensile pull alsoraises the Z-height control tabs 10 above the top of the skirt wall 56,allowing the top of the Z-height control tabs 10 to slide over the topof the skirt wall 56. Additionally, to facilitate assembly it may alsobe advantageous for the end-to-end width of the Z-height control tabs 10to be smaller the end-to-end width of the hooks 48. This can prevent thetabs 10 from getting hung-up on the skirt 36 during assembly.

[0037] In the embodiment of FIG. 2, the reaction housing 12, the hooks48, and the Z-height control tabs 10 are a single piece component. TheZ-height control tabs 10 and the hooks 48 are integrally formed out ofthe reaction housing 12 shoulder portion 44. The housing may be mostrapidly and cost effectively manufactured through a metal stampingprocess. As mentioned above, metal stamping is the process whereby arelatively flat piece of metal is bent and cut into a shape by forcingthe sheet of metal into a form with a press. In one step, a stampingprocess can shape the housing, cut and shape the hooks 48, cut and shapethe tabs 10, and create any airbag mounting holes. The stamping processis less expensive that other single-step processes, such as injectionmolding, but produces a metal reaction housing 12 that is stronger andless time consuming.

[0038] The stamping process is also capable of simply manufacturingmultiple other embodiments of the Z-height control tabs. FIG. 3 depictsan alternative embodiment of these Z-height control tabs 68. In thisembodiment, the Z-height control tab 68 shown does not engage the top ofthe skirt wall 56 as in previously discussed embodiments. Instead, theZ-height control tab 68 engages a window 40 in the skirt 36. TheZ-height control tab 68 to the window 40 engagement is different thanthe engagement of the hook 48 and window 40 fasteners. The hook 48, asshown in FIG. 2, engages the top edge of the window 50, preventing thereaction housing 12 and the airbag cover 20 from being pulled apart. TheZ-height control tab 68 of FIG. 3 engages the lower edge 72 of thewindow 40, preventing the reaction housing 12 and the airbag cover 20from being compressed together. The tab 68 and window 40 in thisembodiment can be placed in multiple locations along the skirt 36. Forexample, the window 40 may be near the top of the skirt wall 56, so thatthe window 40 forms a notch in the top of the skirt 36. The Z-heightcontrol tab 68 would then engage the bottom of the notch.

[0039]FIG. 3 further demonstrates that the Z-height control tab 68 mayextend from the reaction housing 12 at an angle 70 above or below aperpendicular extension. The angled tab 68 may be semi-flexible to placea biasing load on the top of the skirt wall 56, creating an interferencefit. The flexibility and the angle 70 of the tab 68 may also allowtolerances of the reaction housing 12 and the airbag cover 20 to belooser while still obtaining a secure fit. This is accomplished byangling the Z-height control tab 68 so that even when the window 40 isat its largest tolerance and is positioned at its closest to the toppanel, the Z-height control tab 68 will still engage the edge of thewindow 50. Therefore, if the window 40 is smaller or if its position iscloser to the top of the skirt 36, the tab 68 may simply flex to engagethe window 40. An angled Z-height control tab 68 also allows for loosetolerances of the skirt 36 height while still maintaining a net orinterference fit.

[0040] Added advantages may also be obtained by implementing an angledtab, similar to the angled tab 68 depicted in FIG. 3, to the Z-heightcontrol tab 10 embodied in FIG. 2. Referring back to FIG. 2, an angledtab 10 allows the hook 48 and Z-height control tab 68 to bracket-in asection of the skirt 36, so that the wall must deform in order to bereleased from the hook 48 and tab 10 bracket-type engagement. A Z-heightcontrol tab may have a wide range of angles to accommodate variousairbag module designs. For example, the Z-height control tabs 10 in theFIG. 2 embodiment preferably have a 5° to 10° angle offset from aperpendicular extension from the reaction housing 12. This provides theinterference fit and loose tolerance characteristics as discussed above.However, the Z-height control tab may be any angle suitable for thedesired function.

[0041]FIG. 4 depicts another embodiment of a Z-height control tabs 76.In this embodiment, the window in the skirt 36 is a recess 80 in theinterior wall of the skirt 36 instead of a through window. The Z-heightcontrol tab 76 in this embodiment engages the edge of the recess 80 tomaintain the Z-height 16. This recess 80 and tab 76 system may also havean angled tab and an angled recess edge to ensure the tab does not slipoff of the edge of the skirt 36. Additionally, while the recess 80 shownin FIG. 4 is relatively long compared to the thickness of the Z-heightcontrol tab 76, the recess 80 or window 40 does not need to besignificantly larger than the thickness of the Z-height control tab 76.The recess 80 may be the same size as the tab 76, or the recess 80 maybe smaller than the tab 76, creating an interference fit. The shape ofthe Z-height control tabs 76 may also vary depending upon the differentembodiments. While the figures have shown the Z-height control tabs 76as being rectangular shaped, the tabs 76 may take any shape sufficientto maintain the Z-height 16. Rounded or chamfered tab designs may beselected to prevent the tabs 76 from catching when assembled. Oneordinarily skilled in the art will recognize that a multiple number ofZ-height control tab 76 shapes exist that allow for adequate Z-height 16maintenance.

[0042] As it has been demonstrated, the implementation of Z-heightcontrol tabs on a reaction housing will maintain a proper Z-height of anairbag module. Thus, the Z-height can be sufficiently maintained duringcompressive loads with no added cost to the manufacturing process.Additionally, various embodiments of the Z-height control tabs willallow for looser tolerances in the airbag module and a more secure fitbetween the reaction housing and the airbag cover.

[0043] The present invention may be embodied in other specific formswithout departing from its structures, methods, or other essentialcharacteristics as broadly described herein and claimed hereinafter. Thedescribed embodiments are to be considered in all respects only asillustrative, and not restrictive. The scope of the invention is,therefore, indicated by the appended claims, rather than by theforegoing description. All changes that come within the meaning andrange of equivalency of the claims are to be embraced within theirscope.

What is claimed and desired to be secured by United States LettersPatent is:
 1. An airbag module, comprising: a cover and a reactionhousing, wherein the cover or the reaction housing has a plurality ofmounting projections and at least one Z-height control tab, and theother of the cover or the reaction housing comprises a skirt with aplurality of windows corresponding to the mounting projections, suchthat the mounting projections engage the windows to define a Z-height,and the Z-height control tab engaging the skirt to substantiallymaintain the defined Z-height.
 2. The airbag module in claim 1 whereinthe reaction housing is made of stamped metal.
 3. The airbag module inclaim 1 wherein the Z-height control tab engages the skirt at an anglesufficient to prevent substantial Z-height movement.
 4. The airbagmodule in claim 1 wherein the Z-height control tab engages the skirtgenerally perpendicularly to the skirt.
 5. The airbag module in claim 1wherein the reaction housing comprises the Z-height tab and the reactionhousing further comprising a reaction surface.
 6. The airbag module inclaim 5 wherein the Z-height control tab is aligned generally parallelto a plane extending across the surface of the reaction plate.
 7. Theairbag module in claim 5 wherein the Z-height control tab is alignedfrom about 5° to about a 15° angle to the plane extending across thesurface of the reaction plate.
 8. The airbag module in claim 1 whereinthe tab is semi-deflectable.
 9. The airbag module in claim 1 wherein theZ-height control tab engages the skirt in a net fit.
 10. The airbagmodule in claim 1 wherein the Z-height control tab engages the skirt inan interference fit.
 11. The airbag module in claim 1 wherein theZ-height control tab is integrally formed in the cover or the reactionhousing.
 12. The airbag module in claim 1 wherein the skirt has a topedge and the Z-height control tab engages a notch in the top edge. 13.The airbag module in claim 1 wherein the Z-height control tab engage atleast one window in the skirt.
 14. The airbag module in claim 1 whereinthe window is a recess in the skirt
 15. The airbag module in claim 1wherein the cover or the reaction housing comprising the Z-heightcontrol tab has a perimeter edge and the Z-height control tab projectsoutward from perimeter edge to engage the other member.
 16. The airbagmodule in claim 15 wherein the mounting projections extend further fromthe perimeter edge than the Z-height control tab.
 17. The airbag modulein claim 1 wherein the reaction housing has a shoulder and the tab isformed from stamping out a section of the shoulder.
 18. An airbag modulecomprising: a cover having a front panel and a skirt, the skirt having aplurality of windows; and a reaction housing having a plurality ofintegrally formed mounting projections, the mounting projectionsengaging the windows to define a storage volume, the housing furthercomprising at least one integrally formed Z-height control tab engagingthe cover.
 19. The airbag module in claim 18 wherein the Z-heightcontrol tab engage the skirt to maintain a defined Z-height.
 20. Theairbag module in claim 19 wherein the reaction housing is made ofstamped-metal.
 21. The airbag module in claim 18 wherein the Z-heightcontrol tab engages the skirt at an angle sufficient to preventsignificant Z-height movement.
 22. The airbag module in claim 18 whereinthe Z-height control tab engages the skirt at a generally perpendicularengagement.
 23. The airbag module in claim 18 wherein the tab issemi-deflectable.
 24. The airbag module in claim 18 wherein the Z-heightcontrol tab engages the skirt in a net fit.
 25. The airbag module inclaim 18 wherein the Z-height control tab engages the skirt in aninterference fit.
 26. The airbag module in claim 18 wherein the skirthas a top edge and the Z-height control tab engages a notch in the topedge.
 27. The airbag module in claim 18 wherein the Z-height control tabengages at least one window in the skirt.
 28. The airbag module in claim18 wherein the window is a recess in the skirt.
 29. The airbag module inclaim 18 wherein the reaction housing has a perimeter edge and whereinthe Z-height control tab projects outward from the perimeter edge toengage the cover.
 30. The airbag module in claim 30 wherein the mountingprojections extend further from the perimeter edge of the reactionhousing than the Z-height control tab.
 31. The airbag module in claim 18wherein the reaction housing has a shoulder and the tab is formed fromstamping out a section of the shoulder.
 32. A airbag reaction housingcomprising: a cover having a front panel with a plurality of windows;and a metal-stamped reaction housing having a plurality of integrallyformed mounting projections, the mounting projections engaging thewindows to substantially maintain a Z-height in a tensile direction, thereaction housing further comprising at least one integrally formedZ-height control tab engaging the cover to substantially maintain theZ-height in a compressive direction.